תאריך:
ה', 17/05/201812:30-14:00
מיקום:
Wechsler
The genomic basis of social behavior in bees and its similarity to humans:
Social interactions can be divided into two types: affiliative behaviors like parental care that aims
to benefit the recipient and agonistic behaviors like aggression that aims to cause harm. How and
if neurogenomic responses reflect these opposing behaviors is mostly unknown and can enhance
our understanding of the mechanism of social behavior in animals and humans. To investigate this
question, we compared brain gene expression in honey bee workers after exposure to one of two
short social stimuli: exposure to an intruder bee, which evokes aggression (agonistic interaction)
or to a queen larva, which evokes alloparental care (affiliative interaction). Using RNAseq, we
measured the genetic transcriptomic response to these social stimuli in the mushroom bodies, the
high integration area of the bee brain, at three-time points post exposure. The agonistic response
caused time-dependent differential expression of hundreds of genes. Similarly, we found a
dynamic neurogenomic response in the affiliative interaction that changed over time. Surprisingly,
comparison of the gene expression profiles following affiliative and agonistic interactions revealed
that there was a significant number of genes which responded to both conditions with the same
expression pattern. Among the categories, most enriched in these core response genes were those
related to protein folding and nuclear receptor signaling. This finding suggests the existent of core
response molecular pathway related to any social interaction. Also, we found transcriptomic
responses unique to each type of interaction, demonstrating a distinctive molecular signature for
agonistic and affiliative social interactions. The molecular changes are associated with the bees’
response to social signals in future interaction suggesting that the mushroom body transcriptomic
changes are involved in the biological embedding of social experience.
On a followup project, by challenging bees with both of the above mentioned opposite stimuli, one
after the other in the same group, we found that bees’ response to social stimuli can be ranked on
a social responsiveness spectrum from complete unresponsiveness to highly responsive. We
identified three behavioral types bees: Guards (responded only aggressively); Nurses (conducting
only nursing); Social unresponsive (no response to either stimulus). We hypothesized that the
"unresponsive" phenotype also has a unique brain gene expression profile. Using mushroom
bodies transcriptomic we characterize the neurogenomic profile of each behavioral type. As
predicted, we found hundreds of genes with distinct expression patterns in these three behavioral
types although all the group members are sister bees and were exposed to the same stimuli.
Furthermore, the genes that best distinguished between the behavioral types overlap with the core
social responding pathway that we identified above, suggesting that failure in this pathway lead to
a reduction in social responsiveness. Based on this hypothesis, we looked for similarity between
these genes and genes related to autism in human from several resources. In our analysis, we found
a significant overlap between the two sets of genes highlighting two molecular pathways,
chaperons, and nucleic receptors. For control, we compared our bee gene list with genes related to
other human mental syndromes, and other bees’ gene lists related to other conditions with the
autism-related datasets. In both cases, we didn’t find any significant overlaps. This finding
suggests that the overlap between unresponsive bees and autism in human is unique. The finding
supports the hypothesis that similar social behavioral phenotype in bees and humans share a
common mechanism and suggest the existing of conserved genetic toolkits for social behavior.